Single crystal scintillation is a very simple but also very sensitive method of detecting high energy radiation such as x-rays, gamma-rays and high energy particles with energies exceeding a few kilo-electron volt (KeV). In the past century, a large number of crystals have been proposed for potential scintillating applications.
Some commonly used scintillator materials include thallium-activated sodium iodide (NaI(Tl)), bismuth germanate (BGO), cerium-doped gadolinium orthosilicate (GSO), cerium-doped lutetium orthosilicate (LSO) and cerium-doped lutetium yttrium orthosilicate (LYSO). While these known scintillator materials do have some desirable scintillation characteristics which make them suitable for certain applications, each of the materials possesses one or more deficiencies that limit their use in a variety of applications.
For example, medical imaging such as positron emission tomographs (PET) requires crystals with the highest light yield, narrowest energy resolution and fastest decay time. Moreover, PET also requires a crystal with good physical integrity and chemical inertness. However, few of the commercially available scintillator materials can provide all desired properties for PET.
There are some proposals to enhance performances of scintillators including, e.g., adding codopants into LSO and LYSO or treating (oxidizing/reducing) LSO and LYSO. These proposals still have improving spaces since they usually do not effectively decrease the decay time without adversely affecting the light output, do not have stable single crystal growth, and form defects due to non-equal valences in compositions thereof.
Thus, a need exists for improved scintillator compositions that can be efficiently and economically produced and that exhibit characteristics which enhance radiation detection, including, for example, short decay time while maintaining acceptable light output.